This is interesting from a technical point of view and good to know.
But first, the attacker would need to put one “walkie talkie” within an inch* or so of where the owner has the NFC key card. FYI to attackers: the key card doesn’t work when in a stack of credit cards, such as in a wallet in a pocket.
Once you unlock the car you have just ~20 (?) seconds to put the car in drive, otherwise you need to re-authenticate in a new location within the car on the center console. Or if you put the car in park you have to re-authenticate to drive it again. Not so simple to avoid needing to do this since the car puts itself into park automatically when you are stopped and open the door or unbuckle the seat belt, or a driver not in the seat, etc.
This isn’t minimizing the fact that a hack is possible, but it doesn’t give the thief full access to the drive the car indefinitely like the key fob hack in other cars.
The real thing that minimizes the usability of this hack is that most Tesla owners use their phones as the car key using Bluetooth. Maybe it is possible to hack the Bluetooth authentication but I’ve not heard of that.
*the official NFC range is 4 cm
[edit: I just tried using my key card and it didn’t work from 4 cm away. I had to get about 1cm from the hot spot on the car door pillar for it to work. Maybe this is based on where Tesla mounted the sensor or how much power they drive it with. Maybe the hacker tool could over power a sensor and get it to read from further than 4 cm???]
Mike